Methods and systems for concurrent tooth repositioning and substance delivery

ABSTRACT

The present invention provides devices, systems and methods for orthodontic treatment using elastic repositioning appliances while concurrently providing dental and periodontal therapies. Such therapies are traditionally provided with the use of a variety of accessories and devices which are applied when the repositioning appliance is removed from the patient&#39;s mouth. The present invention eliminates the need for such removal and additional devices by incorporating these therapies into the repositioning appliance.

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] The present application is a divisional of U.S. patentapplication Ser. No. 09/666,783 (Attorney Docket No.018563-002000US/AT-00086), filed Sep. 21, 2000, the full disclosure ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] The present invention is related generally to the field ofmedical methods and devices. More particularly, the present invention isrelated to the oral delivery of substances concurrently with therealignment of teeth.

[0003] Orthodontic treatments involve repositioning misaligned teeth andimproving bite configurations for improved cosmetic appearance anddental function. Repositioning is accomplished by applying gentlecontrolled forces to the teeth over an extended period of time. Due tothe limited space within the oral cavity and extensive movements thatsome teeth must undergo, the teeth will often be moved throughout aseries of intermediate patterns to properly arrange the teeth. Forexample, molars may be temporarily moved backwards (distalized) tocreate adequate space for movement of the incisors. Thus, a singlepatient may experience an average of 25-30 stages or alignment patternsbefore achieving the final desired configuration.

[0004] Recently, it has been found that such repositioning may beaccomplished with the use of a series of removable elastic positioningappliances. Such appliances comprise a thin shell of elastic materialthat generally conforms to a patient's teeth but is slightly out ofalignment with an initial or immediately prior tooth configuration.Placement of the elastic positioner over the teeth applies controlledforces in specific locations to gradually move the teeth into the newconfiguration. Repetition of this process with successive appliancescomprising new configurations eventually move the teeth through a seriesof intermediate configurations or alignment patterns to a final desiredconfiguration. A full description of an exemplary elastic polymericpositioning appliance is described in U.S. Pat. No. 5,975,893, and inpublished PCT application WO 98/58596 which designates the United Statesand which is assigned to the assignee of the present application. Boththese documents are incorporated by reference for all purposes.

[0005] In addition to their ease of use, polymeric positioningappliances are generally transparent and impart substantial force on theteeth, due to stiffness of the appliance. The stiffness of an elasticpositioning appliance is a result of the modulus of the thermoformablepolymer materials from which it is made. The higher the modulus of thematerials, the higher the stiffness of the appliance. When a patientpositions such an appliance over a prescribed group of teeth, one ormore of the teeth will provide a base or anchor region for holding thepositioning appliance in place while the stiffness of the polymericmaterial will impart a resilient repositioning force against one or aportion of the remaining teeth. By designing the appliance to cover theteeth, a much larger contact surface area is afforded compared totraditional spring retainers and wire-based appliances.

[0006] As described, the appliances are only effective in repositioningteeth when the appliance is placed over the patient's teeth. Removal ofthe appliance for any reason interrupts the treatment plan and lengthensthe overall period of treatment. Therefore, removal of the applianceshould be minimized for effective and timely treatment. However, anumber of dental and periodontal therapies which may be desired orrequired by the patient may not be effectively utilized while theappliance is in place. Such therapies may be prescribed by apractitioner to improve oral health or they may be requested by thepatient for cosmetic purposes.

[0007] Oral health concerns often include tooth decay, gingivitis, andperiodontitis, to name a few. Tooth decay may be largely prevented orarrested with fluoride treatment. Treatments include toothpastes, gels,rinses and varnishes. Gum disease, such as gingivitis or periodontitis,is caused by bacterial growth associated with dental plaque and calculusdeposits. The most common recommendation for preventing such bacterialgrowth is to mechanically remove the plaque from the tooth surfaces.However, chronic gingivitis and tooth decay have plagued manyindividuals who in fact comply with good oral hygiene methods and plaqueremoval. This may be due to a variety of factors including geneticpredispositions, illnesses, mouth breathing, and medical treatmentprograms.

[0008] In such cases, bacterial control may be accomplished with the useof antibacterial drugs. A common antibacterial agent shown to beeffective in reducing the activity of many common strains of oral florais chlorhexidine. Chlorhexidine is a cationic biguanide microbicide witha broad spectrum of activity against many forms of bacteria and fungi.Therefore, it has been a popular agent in many studies of gingivitisreversal. Chlorhexidine has traditionally been delivered to the oralenvironment through the use of rinses, such as Peridex® (Proctor andGamble). Sustained delivery to the gingiva has also been attempted withthe use of chlorhexidine impregnated dental floss and dental appliances,such as trays or mouthguards.

[0009] Another frequently prescribed antibacterial agent istetracycline. Tetracycline is a broad spectrum antibiotic which iseffective against virtually all common groups of pathogenic bacteria,both gram positive and negative. Tetracycline may be combined with anantifungal agent, such as amphotericin, to provide activity againstfungi. Tetracycline has traditionally been delivered to the oralenvironment through systemic administration, although localized deliveryhas been attempted with the insertion of tetracycline-filled hollowfiber devices into periodontal pockets and the use of tetracycline ladendental appliances, such as trays and mouthguards. In addition, a numberof other antibacterial drugs are available for dental and periodontaltherapy.

[0010] Cosmetic treatments often include tooth bleaching or whiteningand breath freshening products. Discolorations of enamel and dentin mayoccur due to aging, consumption of staining substances (coffee, tea,colas, tobacco), trauma, staining due to systemic tetracycline(antibiotic) therapy, excessive fluoride, nerve degeneration and olddental restorations. Bleaching lightens these discolorations for awhiter or brighter appearance. Typically, a bleaching gel is placed in athin custom-fitted tray that fits over the teeth. The tray is worn atnight for usually 10 to 14 days and may require periodic re-bleachingtreatments for approximately one or two nights every six months. Breathfreshening products are often used by patients to treat halitosis or forenjoyment of the taste. These include a variety of sprays, rinses,mints, gums, or candies, to name a few.

[0011] Many of these therapies require access to the teeth and gingivalmargin which are typically covered by the elastic repositioningappliance when in use. In addition, some of these therapies may best beadministered by localized delivery over extended periods of time whichwould create substantial interruption of the treatment plan. Forexample, low level delivery of antibiotics by sustained release methodsis often desired to treat periodontal disease. Likewise, treatments suchas bleaching and whitening may require interruption of the treatmentplan for up to two weeks. Removal of the appliance during these periodswould lengthen the overall treatment period. In addition, many of thesetherapies require the usage of specific devices, gels, rinses,applicators and instructions for each administration of therapy. Theseaccessories may be costly, bulky and difficult to use.

[0012] Although removal of the appliance should be minimized, it isnecessary to remove the appliance during daily oral hygiene routines,such as brushing and flossing of the teeth. Likewise, the appliance maybe removed from time to time for participation in athletic activities orfor comfort, such as when eating. The ability to temporarily remove suchappliances allows the patient to pursue conventional oral hygiene, butteeth which are covered by the appliances a majority of the time maystill be at an increased risk of dental and periodontal disease.

[0013] It would be desirable to provide improved devices, systems andmethods utilizing elastic repositioning appliances which permit and/orenhance concurrent dental and periodontal therapies. Likewise, it wouldbe desirable to provide such devices, systems and methods which wouldreduce or eliminate the need for additional accessories and/or protocolsto apply such therapies. Further, the devices, systems and methodsshould be economical and easy to use. At least some of these objectiveswill be met by the designs and methods of the present inventiondescribed hereinafter.

SUMMARY OF THE INVENTION

[0014] The present invention provides devices, systems and methods fororthodontic treatment using repositioning appliances, typically elasticpolymeric shells, while concurrently delivering substances to the teethor gums, for example, to provide dental and periodontal and/or cosmetictherapies. Such therapies are traditionally provided with the use of avariety of accessories and devices which are applied using separateappliances, materials, etc. The present invention eliminates the needfor such additional devices by incorporating these therapies into therepositioning appliance. Moreover, the ability to deliver therapeuticand other agents is concurrent with the course of a repositioningprocedure.

[0015] By “concurrent” or “concurrently,” it is meant that the substanceor agent delivery to the teeth occurs during at least a portion of theduration of the repositioning of the teeth. Thus, the substance may bedelivered continuously during the entire duration of the repositioningprocess, i.e. the substance may be present in or on each repositioningappliance in an amount or amounts sufficient to assure that it isreleased to the oral environment at all times the appliance is placedover the teeth. Alternatively, the substance may be present in or on therepositioning appliance(s) at only selected times or over selected timeintervals so that the substances are delivered at spaced-apart timesduring the repositioning process. For example, each successiverepositioning appliance may be preloaded with a bolus of the substanceso that the bolus is delivered to the patient at the outset of use ofeach new appliance. After the initial bolus is depleted, the substancewill not be delivered again until the next successive appliance is used.As an alternative example, the patient could apply an amount of asubstance at a time each day, where the substance is then released overa relatively short time interval and no more substance delivered untilthe next day. A multitude of other particular patterns are alsopossible.

[0016] While the appliances will be particularly intended forrepositioning teeth, most often when used in systems of multiplealigners, t hey may in some instances be useful as drug or substancedelivery devices without the concurrent repositioning of teeth. Inparticular, many of the specific device constructions described beloware themselves novel and useful for substance delivery, and the presentinvention encompasses such devices.

[0017] In a first aspect of the present invention, an oral deliveryappliance comprises an elastic repositioning appliance providing one ormore substances or agents for oral delivery. As previously described,elastic repositioning appliances comprise a thin shell of elasticpolymeric material having cavities shaped to receive and resilientlyreposition teeth from one arrangement to a successive arrangement. Thisis possible because the cavities are shaped to fit a mold of digitallyarranged teeth in the successive arrangement. A full description of anexemplary elastic repositioning appliance shaped in this manner isdescribed in U.S. Pat. No. 5,975,893, and in published PCT applicationWO 98/58596. Placement of the elastic positioner over the teeth appliescontrolled forces in specific locations to gradually move the teeth intothe new configuration. In order to apply sufficient force, the appliancegenerally covers the tooth surfaces and portions of the gingival margin.Thus, both individual repositioning appliances and systems of suchelastic repositioning devices may be used to deliver agents to theunderlying tooth surfaces and gingiva comprising the oral environmentwhile repositioning teeth.

[0018] In a first embodiment, the oral delivery appliance deliversfluoride to the oral environment to prevent or treat tooth decay.Traditionally, fluoride has been delivered to the oral environmentthrough the use of toothpastes, gels, rinses and varnishes, to name afew. The present invention provides fluoride delivery which may be usedin conjunction with traditional applications or may replace certainapplications. Such fluoride may be provided in a number of forms, suchas neutral sodium fluoride, stannous fluoride, hydrogen fluoride, oracidulated phosphate fluoride (APF) gel, for example. Fluoride may bereleasably attached to the elastic repositioning appliance in a numberof forms, as will be described in more detail in later sections, toprovide delivery to the oral environment.

[0019] In a second embodiment, the oral delivery appliance delivers anantibiotic or drug to the oral environment. In the case of antibiotics,delivery of such an agent may inhibit or kill various microorganisms.Antibiotics often used to treat gingivitis and periodontitis includechlorhexidine and tetracycline. Such antibiotics may be releasablyattached to the elastic repositioning appliance in a number of forms, aswill be described in more detail in later sections, to provide deliveryto the oral environment.

[0020] In a third embodiment, the oral delivery appliance delivers ableaching material to the oral environment. Bleaching of the teeth is acommon cosmetic procedure requested of dental practitioners by theirpatients. The active ingredient in standard bleaching gels is carbamideperoxide and is typically present in an 18-37% suspension. Bleachingmaterials, such as carbamide peroxide, may be releasably attached to theelastic repositioning appliance in a number of forms, as will bedescribed in more detail in later sections, to provide delivery to theoral environment.

[0021] In a fourth embodiment, the oral delivery appliance delivers abreath freshener to the oral environment. Breath fresheners are commonlyavailable in a number of flavors and scents, including mint and fruitflavors, derived from essential oils and/or natural or artificialflavorings, to name a few. Such breath fresheners may be releasablyattached to the elastic repositioning appliance in a number of forms, aswill be described in more detail in later sections, to provide deliveryto the oral environment.

[0022] In a second aspect of the present invention, at least some of theelastic repositioning appliances in a system for repositioning teeth arecoupled to means for releasing the agent to the oral environment whenthe appliance is placed over the teeth. Such means may comprise a layerwhich includes the agent. The layer may be formed over at least aportion of the surfaces of the repositioning appliance. These surfacesinclude both the cavity surfaces, the surfaces within the cavities whichcontact the teeth when in place, and the external surfaces, the surfacesof the appliance which contact the cheeks and lips when in place. Thelayer may be comprised of various materials and may take a variety offorms. For example, the layer may consist essentially of the agent. Inother words, the agent may be attached directly to a surface of thepolymer shell of an elastic repositioning appliance. This may beachieved by applying the agent (optionally in an inert carrier ordiluent) itself to the surface utilizing a number of methods, such asspraying, painting and/or dipping. When the repositioning appliance isplaced over the patient's teeth, the agent may then be released to theoral environment.

[0023] Alternatively, the layer may comprise the agent present in or ona carrier or binder which promotes adhesion or attachment to theappliance and/or which creates a matrix from which the agent can bereleased by diffusion or dissolution. In one embodiment, the agent isdissolved in the carrier or binder. In this case, the agent may beprovided in powder or similar form and dissolved in a liquid solvent.The result may be a solution which may be applied to a surface of theshell, typically by spraying, painting and/or dipping, to form a coatingor film. When the repositioning appliance is placed over the patient'steeth, the agent may then be released from the coating to the oralenvironment. Release may be due to activation or deactivation of thecarrier or any other releasing mechanism, such as by enzymes or proteinsin saliva. Or release may be due to degradation of the carrier bycontact with, for example, saliva. In some cases, the binder or carriermay evaporate upon application to the layer to the surface leaving theagent behind. In these cases, the agent may be released in a similarfashion as when the agent is directly attached to the surface, asdescribed above. It may be appreciated that any agent, particularlyfluoride materials, antibiotics, bleaching materials and breathfresheners, may be delivered to the oral environment in this manner.

[0024] In another embodiment, the agent is encapsulated or suspended inthe layer. A common material for suspension of an agent is a semisolidmaterial, such as a gel, jelly or putty. Such a material may be appliedto a surface of the shell by spraying, painting and/or dipping to form acoating or film. Here, as in all cases, suspension is not limited to ascientific definition and may refer to any situation in which a carrierholds, contains, supports or otherwise includes an agent. Alternativelyor in addition, the semisolid material may be deposited in the cavitiesof the polymer shell which are shaped to receive the teeth. The cavitiesmay be filled to any desired level. When the repositioning appliance ispositioned over the teeth, the teeth will directly contact the semisolidmaterial in the cavities and displace any extra material as the teethare inserted into the cavities. Therefore, it is desired to fill thecavities to a level which will avoid excess overflow of the materialfrom the appliance. Delivery of an agent by use of a semisolidsuspension material is common in bleaching treatments and fluoridetreatments, for example. However, such treatments apply the materialwith the use of a tray or generic appliance which does not applyrepositioning forces to the teeth. By modifying a repositioningappliance, as described above, orthodontic treatment may continuethroughout the delivery of such agents. It may be appreciated that anyagent, particularly fluoride materials, antibiotics, bleaching materialsand breath fresheners, may be delivered to the oral environment in thismanner.

[0025] Another common material for encapsulation or suspension of anagent is a controlled-release material. Thus, the layer may be comprisedof a rate-controlling material wherein the rate controlling materialcontrols the rate at which the agent is released from the layer.Controlled-release or rate-controlled materials deliver a predeterminedamount of an agent at a predetermined rate. Often such deliverymaintains a steady-state concentration of an agent in an environmentwithin a desired therapeutic range for a prolonged period of time. Thus,a prescribed dosage may be delivered. In addition, the ability tosustain delivery eliminates the need for repeated applications of theagent for dosed delivery to the oral environment.

[0026] Although such controlled release materials may be provided as asemisolid material, such as a gel, jelly or putty, as described above,these materials may also be provided as a solid material which isattached to the polymeric shell of the repositioning appliance. One typeof controlled-release material comprises a polymer matrix membranewithin which finely dispersed particles of an agent are suspended. Theagent may diffuse through the matrix membrane according to aconcentration gradient. Alternatively or in addition, the agent may bereleased by degradation of the polymer matrix membrane material. Ineither case, the controlled-release material may be provided as a sheetwhich may be laminated to a surface of the shell. The controlled-releasesheet may be layered with the elastomeric polymer and vacuum formed overa mold to form the repositioning appliance. The controlled-releasematerial may be arranged so that it is present on the inside or outsidesurfaces of the appliance depending on the material and desiredapplication. Or, the controlled-release sheet may be laminated or bondedto a surface of the polymeric shell after forming to supply agentdelivery in desired areas. Alternatively, the controlled-releasematerial may be provided as a tablet or similar mass which may beinserted into the polymeric shell of the repositioning appliance. Theagent may then elute from the tablet into the oral environment overtime.

[0027] In another embodiment, the agent may be held within pores of amaterial and may elute out at a controlled rate from the pores. Theagent itself may be absorbed into the pores of the material, or theagent may be suspended in a carrier which is absorbed into the pores ofthe material. In the latter case, the agent may be released from thecarrier by diffusion and/or by controlled degradation of the carriermaterial. This may incorporate a rate-controlling mechanism in additionto the controlled-release of the agent from the pores. As mentioned, insome cases, enzymes in the patient's saliva will activate the release ordegrade the carrier material to release the agent. It may be appreciatedthat the agent may be released by a combination of any of the releasemethods.

[0028] In a further embodiment, the polymeric shell of the repositioningappliance itself comprises a controlled-release material containing theagent. In this case, at least a portion of at least some of thepolymeric shells in a system for repositioning teeth are formed from acontrolled release material wherein the rate controlling materialcontrols the rate at which the agent is released from the shell. Aspreviously described, the controlled-release material may be a providedin the form of a sheet. Thus, the sheet of controlled-release materialmay be vacuum formed over a mold of the patient's teeth to form arepositioning appliance itself. In this manner, no additionalelastomeric materials may be needed to form the appliance. Thecontrolled-release material may be a polymer matrix membrane, a porousmaterial or any suitable material. Controlled-release may be designed sothat the elution rate of the agent corresponds to the repositioning rateof the teeth. The agent may elute throughout the repositioning process,concluding as the teeth reach the desired arrangement prescribed by theappliance.

[0029] In a still further embodiment, the releasing means coupled to atleast some of the repositioning appliances comprises a reservoir formedin the shell of the appliance in addition to the cavity which receivesthe teeth. Typically, a rate controlling membrane is disposed over thereservoir wherein the rate controlling membrane controls the rate atwhich the substance is released from the reservoir. The reservoir may bepre-filled or pre-loaded with an agent or substance for delivery. Inthis case, the appliance may be ready for insertion or use upon removalfrom any packaging without the need of loading the appliance with theagent for delivery. If the releasing means is designed for a singledelivery period, the appliance may be worn throughout the prescribedrepositioning period and then disposed of. If the releasing means isdesigned for multiple delivery periods, the reservoir may be replenishedwith the agent to be released any number of times throughout theprescribed repositioning period. It may be appreciated that any agent,particularly fluoride materials, antibiotics, bleaching materials andbreath fresheners, may be delivered to the oral environment in thismanner.

[0030] In some instances, it may be desirable to change a visualcharacteristic of the polymeric shell of an oral appliance. Suchappliances comprise a polymeric shell having a cavity shaped to beremovably placeable over the teeth and a material on or within the shellthat changes a visual characteristic of the shell. Such a change istypically in response to a change in the environment. In some cases, thevisual characteristic is a color, such as green, red or blue. Thus, theappliance may appear colored or a particular color under certainenvironmental conditions, either in the oral environment or whenremoved. The described material may be a dye which changes color inresponse to a change in temperature. For example, the dye may changecolor when the appliance is removed from the mouth and changestemperature from body temperature (37° C.) to room temperature (25° C.).Similarly, the dye may change color when the appliance is rinsed withcool water.

[0031] In a fourth aspect of the present invention, methods forconcurrently repositioning teeth and delivering agents to the oralenvironment of a patient are provided. For example, one method comprisesplacing a first tooth position adjustment appliance over the patient'steeth, wherein the teeth move to a first tooth arrangement. Afterremoval of the first appliance, a second tooth position adjustmentappliance is placed over the patient's teeth wherein the teeth move to asecond tooth arrangement. Concurrently with the repositioning of theteeth, an agent or substance is released from at least one of the firstand second tooth position adjustment appliances to the oral environmentwhile the appliance is in place of the patient's teeth.

[0032] Although the appliance may be pre-loaded with the agent and readyfor use upon removal from any packaging, appliances that are notpre-filled or pre-loaded may require loading prior or immediately priorto placing the appliance over the teeth. Loading may comprise placingthe agent in a teeth-receiving cavity. As described previously, thecavities may be filled to any desired level. When the appliance ispositioned over the teeth, the teeth will directly contact the agent inthe cavities as the teeth are inserted into the cavities. Alternatively,loading may comprise placing the agent into an agent release reservoirin the appliance immediately prior to placing the appliance over theteeth. The agent will then elute from the reservoir into the oralenvironment when the appliance is in place over the teeth. The elutionrate may be controlled by a controlled release membrane which separatesthe reservoir from the surrounding environment. Loading may alsocomprise adhering a rate controlling material containing the agent to asurface of the appliance prior to placing the appliance over the teeth.Such a material may comprise a polymer matrix membrane which may beremovably or permanently adhered to the polymeric shell of the appliancein desired areas for delivery of the agent. And finally, loading maycomprise absorbing the agent into a porous material on or within theappliance immediately prior to placing the appliance over the teeth.

[0033] Repositioning of the teeth with the use of a position adjustmentappliance involves placing the appliance over the teeth. However, theappliance is periodically removed for daily dental hygiene practices andother events throughout the repositioning protocol until the teeth aremoved to at least near the desired tooth arrangement. While theappliance is removed from the teeth, the appliance may be replenishedwith the agent or substance for delivery. Replenishment may be performedimmediately prior to each time the appliance is replaced over the teethor it may be performed according to any prescribed protocol.

[0034] In a fifth aspect of the present invention, methods forintroducing agent delivery to a prescribed tooth repositioning treatmentplan are provided. A treatment plans is determined by an orthodontist orpractitioner at the outset of orthodontic treatment. The plan involvesmoving the teeth through a series of intermediate configurations orarrangements to a final desired arrangement with the use of a system oftooth positioning appliances. Each appliance comprises a polymeric shellhaving cavities which is removably placeable over the teeth and whereinthe cavities of successive shells are shaped to reposition teeth fromone arrangement to a successive arrangement according to the treatmentplan. The entire series of appliances may be provided at the outset oftreatment, or a subset of appliances. In any case, the need or desirefor delivery of an agent to the oral environment may occur at any pointduring the course of treatment. In such a case, an agent and/or meansfor releasing an agent to the oral environment may be coupled to anappliance at any time during treatment.

[0035] Means for releasing the agent may include a number ofembodiments, including any such means previously described. Typically,means for releasing the agent comprises a layer including the agent, aspreviously described, and coupling comprises adhering the layer to atleast a portion of a surface of the appliance. When the layer consistsessentially of the agent, adhering may involve coating, spraying,dipping or painting the agent on the surface of the appliance. Thus, apre-formed appliance may simply be coated with the agent prior toinsertion in the patient's mouth. When the layer comprises an agentpresent in or on a carrier or binder, adhering may involve attaching thecarrier or binder a surface of the appliance. Similarly, when the agentis encapsulated in the layer, the layer may be attached to the surfaceof the appliance. The layer may comprise a sheet of rate controllingmaterial wherein the rate controlling material controls the rate atwhich the agent is released from the layer. In this case, the sheet maybe bonded to the surface of the appliance with an adhesive.Alternatively, the sheet may be attached to the surface by pressfitting. The sheet and the surface may each be shaped so that they snapor fit together by pressing them together. For example, the sheet mayhave a formed protrusion and the surface a formed inset, wherein theprotrusion fits into the inset when pressed upon the inset and holds thesheet in place. In many instances, the appliance may be porous or have areservoir which can be loaded with a desired agent at any time thetreating professional and/or the patient decide that it is appropriate.For example, an appliance can be immersed in a solution f the agent,allowing the appliance to absorb or adsorb the agent at a particulartime.

[0036] In addition, the sheet may be pre-formed to a shape adapted forfitting against the surface of the appliance or a surface of the teethor gingiva. For example, the sheet may be pre-formed to reflect theshape of the surface of one or more teeth or the gingiva, particularlyalong the gingival margin. The preformed sheet may then be held againstthat surface when the sheet is coupled to the appliance and theappliance is placed over the teeth. Coupling may involve any means ofattaching the sheet to the appliance. In particular, the pre-formedsheet may further comprise an adhesive layer which may provide bondingof the sheet to the surface of the appliance.

[0037] Other objects and advantages of the present invention will becomeapparent from the detailed description to follow, together with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038]FIG. 1 is a schematic illustration of an exemplary elasticrepositioning appliance.

[0039]FIG. 2 is a cross-sectional view along line 2-2 of therepositioning appliance of FIG. 1 with a layer comprising an agent onits surface.

[0040]FIG. 3 is a cross-sectional view of an appliance having asemisolid material containing an agent applied to its surface.

[0041]FIG. 4 is a cross-sectional view of an appliance having a cavityfilled with a semisolid material containing an agent.

[0042]FIG. 5 illustrates the layering of a sheet of controlled-releasematerial containing an agent with a polymeric sheet for use in theformation of an oral delivery appliance.

[0043]FIG. 6 illustrates the attachment of a controlled-release materialto the polymeric shell of an appliance and the insertion of acontrolled-release tablet into a portion of the polymeric shell.

[0044]FIG. 7 illustrates a reservoir type releasing means having sealedends.

[0045]FIG. 8 illustrates a reservoir type releasing means that isaccessible to the user so that the reservoir may be replenished with anagent.

[0046]FIG. 9 is a cross-sectional view of an appliance having a bindingmaterial and releasably bound agent applied to its surface.

[0047]FIG. 10 is a cross-sectional view of an appliance comprised of acontrolled-release material containing an agent.

[0048]FIG. 11 illustrates a gradual color change of an appliance fromtransparent to colored as the appliance changes in temperature.

[0049]FIG. 12 depicts the use of a color or dye localized in a specificarea; examples of a stripe formed in the appliance and a portion ofcolored material affixed to a surface are shown.

[0050]FIG. 13 illustrates the positioning of an appliance of the presentinvention over the teeth of the patient.

[0051]FIG. 14 is a perspective view of a pre-formed sheet 60 of materialcontaining an agent may have a shape contoured to fit against a surfaceof an appliance.

[0052]FIG. 15 is a perspective view of the pre-formed sheet of FIG. 14fit over an outside surface of an appliance.

[0053]FIG. 16 is a side view of a pre-formed sheet of materialcontaining an agent, contoured to fit against a surface of the teeth andgingiva, together with a side view of an appliance to which it may bejoined.

[0054]FIG. 17 is a side view of the pre-formed sheet and appliance ofFIG. 16 joined with an adhesive layer.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

[0055] An oral delivery appliance of the present invention comprises anelastic repositioning appliance which concurrently provides orthodonticrepositioning forces and dental therapies. FIG. 1 depicts an exemplaryelastic repositioning appliance 10 used for orthodontic treatment. Theappliance 10 comprises a polymeric shell 12 having cavities 14 shaped toreceive and resiliently reposition teeth from one tooth arrangement to asuccessive tooth arrangement. The appliance 10 is preferably formed froma thin sheet of a suitable elastomeric polymer, such as Tru-Tain 0.03in. thermal forming dental material (Tru-Tain Plastics, Rochester,Minn.), or Essix A-Type or Essix B-Type thermal forming material(Raintree-Essix, New Orleans, La.). The overall method for producingincremental position adjustment is provided in U.S. Pat. No. 5,975,893,previously incorporated by reference. But, in general, the shell 10 istypically produced by heating a thermoformable polymer sheet and vacuumor pressure forming the sheet over tooth members of a mold. Thus, theshell 12 is a direct representation of the characteristics of the mold.If this appliance 10 is worn by a patient as a stage in orthodonticrepositioning, the shell 12 will preferably, but not necessarily, fitover all teeth or dental features supported by the patient's dentalarch. Those teeth which are to be repositioned will be slightly misfitby the appliance to allow force and movement into the desired positions.

[0056] Dental and periodontal therapies may be simultaneously deliveredby such an elastic repositioning appliance to provide uninterruptedorthodontic treatment while treating other conditions. Such therapiesinclude fluoride treatment to prevent or treat tooth decay, antibioticor drug therapy to treat gingivitis and periodontitis, bleaching toimprove the cosmetic appearance of the teeth, and/or breath fresheningto treat halitosis. In addition, such an elastic repositioning appliancemay also comprise a material which changes a visual characteristic ofthe shell in response to a change in the environment, as statedpreviously.

[0057] Each of the above identified therapies involves one or moretherapeutic agents which are delivered to the oral environment. Thepresent invention provides a tooth positioning appliance coupled tomeans for releasing one or more of these agents to the oral environment.Agents for the above identified therapies include, but are not limitedto, various forms of fluoride, such as neutral sodium fluoride andstannous fluoride, various antibiotics, such as chlorhexidine andtetracycline, bleaching ingredients, such as carbamide peroxide, andbreath fresheners or flavors. Means for releasing the agent may includea number of embodiments.

[0058] In one embodiment, means for releasing the agent to the oralenvironment comprises a layer including the agent formed over at least aportion of the surfaces of the polymer shell. Such a layer may comprisethe agent 15 itself. This is illustrated in FIG. 2, which depicts across-sectional view (along line 2-2 of FIG. 1) of a polymer shell 12having cavities 14, shaped to receive and resiliently reposition teeth,and an agent 15 attached to its surface. It may be appreciated that thedepictions of the agent is for illustration purposes and does notnecessarily reflect the actual shape, size relationship or distributionof the agent particles. This applies to all depictions of agentshereinafter. Such attachment or formation of the layer may be achievedby applying the agent 15 to the surface of the shell 12 by a number ofmethods, including spraying, painting and/or dipping. Thus, when theoral delivery appliance 20 is placed over the patient's teeth, the agentmay then be released to the oral environment. When the agent 15 isattached to the inside surface of the appliance 20, as shown in FIG. 2,the agent may directly contact the teeth and/or gingiva. This may bebest suited for treatments such as fluoride or antibiotic therapy whichbenefit from direct contact with the teeth and/or gingiva. However,other treatments, such as breath freshening, may most benefit fromattachment to the outer surface of the appliance 20. Therefore, agents15 may be attached to any or all surfaces of the appliance 20.

[0059] In another embodiment, the layer comprises the agent 15 presentin a carrier or binder. A common carrier for suspension of an agent is asemisolid material, such as a gel, jelly or putty. As depicted in FIG.3, such semisolid material 22 may be applied to the surface of the shell12 by spraying, painting and/or dipping to form a coating or film.Alternatively, as depicted in FIG. 4, the semisolid material 22 may bedeposited in the cavities 14 of the polymer shell 12 which are shaped toreceive the teeth. The cavities 14 may be filled to any desired levelsuch that when the appliance 20 is positioned over the teeth, the teethwill directly contact the material 22 and displace any extra material22. Delivery of an agent 15 by the use of such a material 22 is mostcommon in bleaching and fluoride treatments, however any type of agent15 may be used.

[0060] Another type of layer is a controlled-release materialimpregnated with the agent, wherein the rate controlling materialcontrols the rate at which the agent is released from the layer.Controlled-release or rate-controlled materials deliver an agent at apredetermined rate. As previously described, such delivery may beachieved by a number of methods. First, the agent may be released bydiffusion through the controlled-release material. In this case, theagent is typically present as finely dispersed particles in a polymermatrix membrane. This is often termed a monolithic dispersed typesystem, monolithic device, or matrix diffusion system. As theconcentration of agent is reduced in the matrix due to diffusiondelivery to the oral environment, the slope of the drug diffusion curveis also reduced. The agent delivery rate decreases over time as thematerial is depleted. Hence, the characteristic release profile of amonolithic system follows an asymptotic curve; after an initial burst ofrapid release, the elution approaches a constant rate. Second, the agentmay be released by degradation of the controlled-release material.Degradation may be achieved by a number of mechanisms, includingenzymatic degradation by enzymes in the saliva. The agent may beencapsulated or contained in a biodegradable material, such as a polymermatrix. Any number of degradation rates may be achieved by manipulatingthe molar ratio of the monomers in the matrix. Further, the agent may bereleased by a combination of diffusion and degradation of the releasinglayer. Alternatively or in addition, the agent may be released byelution from pores within the releasing layer. Depending on thestructure of the layer, elution from the pores may be achieved by anumber of methods. If the agent is contained in a controlled-releasematerial which fills the pores, the agent may be released from thecontrolled-release material by diffusion and/or degradation and thenelution from the pores themselves.

[0061] One attribute of controlled-release materials is that they may beprovided in a solid form, such as a thin film or sheet, which may beattached to the polymeric shell of an elastic repositioning appliance.Referring to FIG. 5, a controlled-release material 24 containing theagent 15 may be provided as a sheet 25 and used in the formation of anappliance of the present invention. Here, the sheet 25 may be layeredwith an elastomeric polymer sheet 28 over a mold 30 of the patient'sdentition. Together the sheets 25, 28 may be vacuum formed over the mold30 to form the repositioning appliance. By placing thecontrolled-release material sheet 25 between the mold 30 and the polymersheet 28, as shown, the controlled-release material 24 will cover theinside surfaces of the appliance and will be positioned against thepatient's teeth and/or gums when the appliance is in place. This may bemost beneficial for elution of agents 15 such as fluoride, antibioticsor bleaching materials.

[0062] Alternatively, the controlled-release material 24 may be attachedto the polymeric shell 12 of the oral delivery appliance 20 afterforming the appliance. As shown in FIG. 6, the controlled-releasematerial 24 containing the agent 15 may be laminated, bonded orotherwise attached to a surface of the polymer shell 12 in a desiredarea. Such attachment may be removable, so that the material 24 may beremoved when the agent 15 has substantially eluted or the therapy is tobe discontinued, or it may be non-removable, so that the material 24 ispresent throughout the life of the appliance. Also shown in FIG. 6 isthe use of a controlled-release tablet 34 which may be inserted into apocket 36 or portion of the polymeric shell 12 of the appliance 20.Portions of the pocket may be perforated or meshed to facilitatedelivery of the agent. The agent may then elute from the tablet 34 intothe oral environment over time. This design may be most applicable toelution by degradation of the tablet 34, wherein the tablet 34 may bereplaced periodically for renewed delivery.

[0063] In a further embodiment, the releasing means comprises areservoir formed in the polymer shell in addition to the cavity whichreceives the teeth. Reservoir devices or membrane diffusion systems cansupply an agent or substance at a constant rate under sink conditions.These systems consist of three elements: a reservoir containing theagent, a low concentration sink, such as the oral environment, and arate-controlling membrane separating the reservoir from the sink. Thesystem obeys Fick's Law of Diffusion for the mass flux across themembrane. Thus, the system is held at a constant delivery rate based onthe diffusion coefficient through the membrane.

[0064] Referring to FIG. 7, the releasing means is shown to comprise areservoir 60 formed in the polymer shell 12, in addition to the cavity14 which receives the teeth. The reservoir holds the agent 15 and iscovered by a rate controlling membrane 62 which controls the rate atwhich the agent 15 is released from the reservoir 60. The reservoirs 60are depicted as being located substantially within the wall of thepolymer shell 12 for elution to the cavity 14. However, it may beappreciated that reservoirs 60 may be located anywhere in the shell 12,may be external to the wall of the shell 12 and may elute in anydirection. The reservoirs 60 may be pre-filled with the agent 15 to bereleased. That is, the appliance 20 is provided with the reservoirs 60filled with the agent 15. In this case, the reservoirs 60 may be sealedby the membrane 62 as depicted in FIG. 7. However, the reservoirs 60 mayalso be accessible to the user so that the reservoir may be replenishedwith agent 15 as desired. In this case, the reservoir 60 may be not besealed by the membrane 62 as depicted in FIG. 8.

[0065] In another embodiment, the agent 15 is supported by a carrier. Asdepicted in FIG. 9, the carrier comprises a binding material 40 whichreleasably binds the agent 15 to a surface of the polymeric shell 12.The binding material 40 may release the agent 15 by a number ofmechanisms, including dissolution of the binding material 40, activationor deactivation of the binding material 40 or any other releasemechanism.

[0066] In a further embodiment, as depicted in FIG. 10, the polymericshell 12 of the oral delivery appliance 20 is comprised of acontrolled-release material 42 containing an agent 15. In this case, thecontrolled-release material 42 itself is formed to function as arepositioning appliance. This may be achieved by vacuum forming a sheetof controlled-release material over a mold of the patient's teeth. Theagent 15 may then elute from the appliance 20 by means of diffusion orother release mechanisms.

[0067] Means for releasing the agent to the oral environment have beendescribed in a number of embodiments, above, in regards to the agentitself. However, in each embodiment, the agent may first be encapsulatedor microencapsulated in a material, typically a polymer. Suchencapsulation may be desired or necessary to protect the agent from theeffects of processing. For example, some agents may be hydrolyzed ordenatured by processes such as extrusion or thermoforming which may beinvolved in the production of the appliance. Encapsulation may alsoprotect the agent from environmental factors throughout the shelf-lifeof the appliance. Therefore, in the above descriptions and throughout,“agent” may identify the agent itself or an encapsulated agent.

[0068] Agents may be encapsulated or entrapped by a number of materials.Such materials may include polylactic acids, polycapric lactones,polyvinyl alcohols, polyacrylic acids, polyethylene oxides, polylactideglycolic biodegradable polymer capsules and side-chain crystalizablepolymers, to name a few. Encapsulation may be achieved by a variety ofprocesses. Particularly, the agent may be encapsulated by spray-drying.For example, the agent may be mixed or combined with a solvent, such aspolyvinyl alcohol, and then combined with a polymer resin. After thesolvent evaporates, polymer microcapsules, each containing the agentdispersed throughout its matrix, are retained.

[0069] The encapsulating or entrapping material may or may not providecontrolled-release of the agent from the microsphere. If theencapsulating material does provide controlled-release capabilities,such a layer would be in addition to any controlled-release means forreleasing the agent previously described. For example, the encapsulatedagent may be dispersed throughout a sheet of controlled-release materialwhich is later attached to the polymeric shell of an elasticrepositioning appliance. When the appliance is positioned in thepatient's mouth, the agent may elute at a controlled rate based on therelease of the agent from the encapsulating material and from the sheetof controlled-release material.

[0070] Similiarly, the encapsulating material may be an ion exchangeresin. Such resins have a very high surface area and are able to absorba large quantity of an agent for controlled-delivery. An exemplary resinis sold under the trademark MICROSPONGE (Advanced Polymer Systems), anddescribed, for example, in U.S. Pat. No. 5,145,675, the full disclosureof which is incorporated herein by reference. In addition to serving asan encapsulating material, ion exchange resins may be used for as acontrolled-delivery material in any of the above described embodiments.

[0071] In some instances it may be desirable to change a visualcharacteristic of the polymeric shell of an oral appliance. Suchappliances comprise a polymeric shell 12 having a cavity 14 shaped to beremovably placeable over the teeth and a material on or within the shellthat changes a visual characteristic of the shell. Such a change istypically in response to a change in the environment. For example, thematerial may be a dye which changes color when the appliance is removedfrom the patient's mouth and changes temperature due to the change inenvironment. This gradual color change is illustrated in FIG. 11. Forexample, as shown, a transparent oral delivery appliance 40 will remaintransparent when it is in the mouth and maintained at body temperature.Upon removal from the mouth, the appliance will cool to roomtemperature. As the appliance begins to cool, the colorant willgradually become visible, as illustrated in the tinted oral deliveryappliance 42. As the appliance equilibrates to room temperature, thecolorant will become more visible, as illustrated in the colored oraldelivery appliance 44.

[0072] The color may be dispersed throughout the appliance, as in FIG.11, or the color may be localized in a specific area within or on asurface of the appliance. As shown in FIG. 12, the appliance 20 maycontain, for example, a stripe 46 of color or dye in a specificlocation. Such a stripe 46 may be visible at all times or it may onlyappear when removed from the oral environment. In either case, thestripe 46 may be positioned so that it is hidden from view, i.e. alongthe lingual surfaces or along the molars, or it may be placed anywherealong the appliance. 20. Likewise, a portion of material 48 whichchanges a visual characteristic may be attached, bonded or laminated toa surface of the polymer shell 12, either removably or permanently.

[0073] Methods for concurrently repositioning teeth and deliveringagents to the oral environment of a patient involve the utilization ofat least one tooth position adjustment appliance having a means forreleasing an agent as described above. Typically, repositioning of theteeth involves placing a first repositioning appliance over thepatient's teeth wherein the teeth move to a first tooth arrangement.After the teeth have moved to this arrangement, the appliance isreplaced with a second repositioning appliance which is placed over thepatient's teeth to move the teeth to a second tooth arrangement. This iscontinued with a succession of appliances until the teeth are moved to adesired arrangement. Concurrent delivery of an agent is accomplished byreleasing the agent from at least one of the repositioning applianceswhile the appliance is in place over the patient's teeth. Means forreleasing the agent may include any of the means described previously.

[0074] Referring to FIG. 13, simply positioning the appliance 20 overthe patient's teeth 50 may deliver the agent 15 to the oral environment.It may be appreciated that the agent 15 is enlarged in FIG. 13 toillustrate the presence of the agent 15 in the appliance 20. In manycases, the dispersed agent 15 is so fine that the appliance 20 appearstransparent. In other cases, the agent 15 may be present at a densityhigh enough to be visible. When the appliance 20 is pre-loaded orpre-filled with agent 15, the appliance 20 may be removed from thepackaging and immediately inserted in the patient's mouth, as shown inFIG. 13. However, appliances that are not pre-filled may require loadingprior to placing over the teeth. Loading may comprise placing the agent15 in a teeth-receiving cavity 14, as previously shown in FIG. 4.Alternatively, loading may comprise placing the agent 15 into an agentrelease reservoir 60, as shown in FIG. 8. Loading may also compriseadhering a rate-controlling or controlled-release material 24 containingthe agent 15 to a surface of the appliance 20, as shown in FIG. 6.

[0075] Although some of these loading methods may require speciallydesigned appliances, a number of these methods may be applied to anyposition adjustment appliance. For example, a series of repositioningappliances may be generated according to a treatment plan and providedto a patient. At any point during the treatment plan, delivery of anagent to the oral environment may be necessary or desired. Thepractitioner or the patient may then load the appliance with the agentor agent delivery means and continue with the treatment plan. This maybe easily accomplished with the use of a strip of controlled-releasematerial containing the agent. The strip may be adhered to any surfaceof the appliance with adhesive or any suitable means of attachment.Similarly, any type of agent delivery layer may be attached to theappliance for this purpose. For example, a pre-formed sheet of materialencapsulating the agent may be used wherein the form comprises a shapewherein at least a portion of the shape is contoured to fit against thesurface of an appliance or a surface of the teeth or gingiva. As shownin FIG. 14, the pre-formed sheet 60 of material containing the agent 15may have a shape contoured to fit against an outside surface of theappliance 10. Shown in FIG. 15, the material 60 may be adhered to thesurface with adhesive or may be press-fit to the surface and thereforeheld in place by compressive forces or friction. Similarly, thepreformed sheet of material may have a shape contoured to fit against asurface of the teeth or gingiva. As shown in FIG. 16, the pre-formedsheet 62 containing the agent 15 may be shaped to fit against thegingival margin, thus having contours reflecting the gumline. The sheet62 may then be joined with the appliance 10, as illustrated by thejoining arrows in FIG. 16. Referring to FIG. 17, the sheet 62 and theappliance 10 may be bonded together by an adhesive layer 64 to form anappliance which provides agent delivery. the sheet 62 may be flexible toaccommodate easy attachment of the sheet 62 to the appliance 10 andpositioning and removal of the appliance over the patient's teeth.

[0076] The repositioning appliances may be periodically removed fordaily dental hygiene practices and other events throughout therepositioning protocol or treatment plan until the teeth are moved to atleast near the desired tooth arrangement. While the appliance is removedfrom the teeth, the appliance may be replenished with the agent orsubstance for delivery. Replenishment may be performed immediately priorto each time the appliance is replaced over the teeth or it may beperformed according to any prescribed protocol.

What is claimed is:
 1. An oral appliance comprising: a polymeric shell having cavities shaped to fit a mold of digitally arranged teeth; and means for releasing an agent to the oral environment when the appliance is in place over the patient's teeth, said releasing means comprising a reservoir formed in the shell in addition to the cavity which receives the teeth.
 2. An appliance as in claim 1, wherein the agent comprises a material selected from the group consisting of fluoride, an antibiotic, a bleaching material, a flavor and a scent.
 3. An appliance as in claim 2, wherein the agent comprises at least two materials selected from the group.
 4. An appliance as in claim 1, wherein said releasing means further comprises a rate controlling membrane which controls the rate at which the agent is released from the reservoir.
 5. An appliance as in claim 4, wherein the reservoir is sealed by the rate controlling membrane.
 6. An appliance as in claim 4, wherein the reservoir is accessible for replenishing with agent.
 7. An oral appliance comprising: a polymeric shell having cavities shaped to be removably placeable over teeth; and a material on or within the shell that changes a visual characteristic of the shell in response to a change in temperature.
 8. An oral appliance as in claim 7, wherein the visual characteristic is a color.
 9. An oral appliance as in claim 7, wherein the material is a dye which changes color in response to the change in temperature.
 10. An agent delivery device for use in combination with a dental appliance which fits over the teeth, said device comprising: a sheet of material including the agent adapted for fitting against a surface of the dental appliance, wherein the material comprises a non-porous rate controlling polymer matrix which controls the rate at which the agent diffuses through the polymer matrix and is released.
 11. An agent delivery device as in claim 10, wherein the agent comprises a material selected from the group consisting of fluoride, an antibiotic, a bleaching material, a flavor and a scent.
 12. An agent delivery device as in claim 10, further comprising an adhesive layer, wherein the adhesive layer bonds the sheet to the appliance.
 13. An agent delivery device for use in combination with a dental appliance which fits over the teeth, said device comprising: a sheet of material including the agent adapted for fitting against a surface of the dental appliance, wherein the material comprises a rate controlling polymer matrix which degrades to release the agent.
 14. An agent delivery device as in claim 13, wherein the agent comprises a material selected from the group consisting of fluoride, an antibiotic, a bleaching material, a flavor and a scent.
 15. An agent delivery device as in claim 13, further comprising an adhesive layer, wherein the adhesive layer bonds the sheet to the appliance.
 16. A system for repositioning teeth and releasing an agent to an oral environment, said system comprising: at least three tooth positioning appliances, wherein said appliances comprise polymeric shells having cavities, which are removably placeable over the teeth and wherein the cavities of successive shells are shaped to reposition teeth from one arrangement to a successive arrangement; means coupled to at least some of the appliances for releasing the agent to the oral environment when the appliance is in place over the teeth, wherein said releasing means comprises a reservoir formed in the shell in addition to the cavity which receives the teeth and a rate controlling membrane disposed over the reservoir wherein the rate controlling membrane controls the rate at which the agent is released from the reservoir.
 17. A system as in claim 16, wherein the reservoir is pre-filled with the agent to be released.
 18. A system as in claim 16, wherein the reservoir is replenishable with the agent to be released.
 19. A system as in claim 16, wherein the agent comprises the agent microencapsulated in a polymer material.
 20. A system as in claim 16, wherein the agent is released by diffusion through the membrane.
 21. A system as in claim 16, wherein the agent is released by degradation of the membrane.
 22. A system as in claim 16, wherein the rate controlling membrane is porous and the agent is released by elution through the pores.
 23. A system as in claim 16, wherein the agent comprises a material selected from the group consisting of fluoride, an antibiotic, a bleaching material, a flavor and a scent.
 24. A system as in claim 23, wherein the agent comprises at least two materials selected from the group.
 25. A system as in claim 23, wherein the material is a fluoride selected from the group consisting of acidulated phosphate fluoride gel, neutral sodium fluoride, hydrogen fluoride and stannous fluoride.
 26. A system as in claim 23, wherein the material is an antibiotic selected from the group consisting of tetracycline and chlorhexidine.
 27. A system as in claim 23, wherein the material is carbamide peroxide.
 28. A system as in claim 23, wherein the material is a flavor or scent selected from the group consisting of essential oils, natural flavorings and artificial flavorings. 